Digital Electro-Hydraulic Control System (DEHC)

Question 1

What is the Purpose of DEHC?

Answer 1

Maintain Reactor pressure set point by positioning Main turbine steam supply and bypass valves

Question 2

When does the STBY pump start.

Answer 2

System pressure <1300#

Question 3

What is Drop2/52?

Answer 3

Redundant pair of controllers used for turbine protection functions

Question 4

What is Power Load Unbalance?

Answer 4

1. Compares Generator Current (amps) and Cross around piping pressure (43% mismatch)
2. Active when Generator loaded to greater than 42.8%.
3. =load reject

Question 5

What happens on a loss of air to the EHC HPU drain cooler temp control valve?

Answer 5

Fails Open

Question 6

What happens on a loss of CCS?

Answer 6

EHC reservoir temperature will go up and ultimately affect EHC pump NPSH

Question 7

How long will BPV accumulators hold BPVs open?

Answer 7

1 min after Turbine trip

Question 8

Purpose of Fullers Earth

Answer 8

Maintains the fluid at a low neutralization number by absorbing acids and water and maintains the chlorine content of the fluid within the recommended limits.

Question 9

What actions need to be taken when resetting the Turbine and DEHC Speed automatically selects 1800 RPM?

Answer 9

Operator has approximately 10 seconds to select ALL VALVES CLOSED to prevent NSSS MSIV isolation on low vacuum trip due to Turbine Stop Valves opening. (N2-OP-21_D.10)

Question 10

What does 20% Bypass Valve Jack Target equal in regard to Bypass valves?

Answer 10

1 BPV full open

Question 11

When do BPV go closed in regard to Condenser vacuum?

Answer 11

7” Hg

Question 12

What doe the colors Gray or Orange mean on the Drops?

Answer 12

INOP

Question 13

What does a loss of IAS do to the EHC HPU drain cooler temp control valves?

Answer 13

Fail Open
MAX Cooling

Question 14

What does Main Generator 86 mean?

Answer 14

armature fault